A new synthetic approach using the Pluronic P123-assisted hydrothermal reaction of lanthanum phosphate and europium-doped lanthanum phosphate has been developed, which results in the formation of uniform spindle-shaped microarchitectures most probably by a self-assembly process. Our results reveal that the obtained spindle-shaped microarchitectures consist of several tens of aligned single-crystalline nanowires with smooth, well-defined facets and highly uniform morphologies. These well-defined spindle-shaped microarchitectures show greatly enhanced photoluminescence in these compounds when compared to their counterparts of disordered arrangements. A possible formation mechanism for these spindle-shaped microarchitectures is presented and discussed.